plot.im
Plot a Pixel Image
Plot a pixel image.
Usage
## S3 method for class 'im':
plot(x, \dots, col=NULL,
ribbon=TRUE, ribsep=0.15, ribwid=0.05, ribn=1024,
ribscale=1)
Arguments
- x
- The pixel image to be plotted.
An object of class
"im"
(seeim.object
). - ...
- Extra arguments passed to
image
to control the plot. - col
- Colours for the pixel values. Either a character vector of colours,
or an object of class
colourmap
. - ribbon
- Logical flag indicating whether to display a ribbon showing the colour map.
- ribsep
- Factor controlling the space between the ribbon and the image.
- ribwid
- Factor controlling the width of the ribbon.
- ribn
- Number of different values to display in the ribbon.
- ribscale
- Rescaling factor for tick marks. The values on the numerical scale printed beside the ribbon will be multiplied by this rescaling factor.
Details
This is the plot
method for the class "im"
.
[It is also the image
method for "im"
.]
The pixel image x
is displayed on the current plot device,
using equal scales on the x
and y
axes.
If ribbon=TRUE
, a legend will be plotted at the right of the
image. The legend consists of a colour ribbon and an axis with tick-marks,
showing the correspondence between the pixel values and the colour map.
Arguments ribsep, ribwid, ribn
control the appearance of the
ribbon.
The width of the ribbon is ribwid
times the size of the pixel
image, where `size' means the larger of the width and the height.
The distance separating the ribbon and the image is ribsep
times
the size of the pixel image. The ribbon contains ribn
different numerical values, evenly spaced between the minimum and
maximum pixel values in the image x
, rendered according to
the chosen colour map.
The pixel values are displayed using the colours given in the
argument col
. This may be either an explicit colour map
(an object of class "colourmap"
, created by the function
colourmap
) or a character vector or integer vector
that specifies a set of colours.
If col
is an explicit colour map
(an object of class "colourmap"
) then the same colour
always represents the same numeric value. For example this ensures
that when we plot different images, the colour maps are consistent.
If col
is a character vector or integer vector that specifies
colours, then the colour mapping will be stretched to match the range of
pixel values in the image x
. In this case, the mapping of pixel values
to colours is determined as follows.
[object Object],[object Object],[object Object]
Other graphical parameters controlling the display of both the pixel image
and the ribbon are passed through the ...
arguments
directly to the function image.default
.
To suppress the axis tick marks and labels, set axes=FALSE
.
Value
- none.
See Also
im.object
,
colourmap
,
contour.im
,
persp.im
,
image.default
,
spatstat.options
Examples
# an image
Z <- setcov(owin())
plot(Z)
# stretchable colour map
plot(Z, col=terrain.colors(128), axes=FALSE)
# fixed colour map
tc <- colourmap(rainbow(128), breaks=seq(-1,2,length=129))
plot(Z, col=tc)